1. Field of the Invention
This invention relates to a light emitting element (e.g., an light-emitting diode (LED)) with two electrodes formed on the same side as well as a method of making the light emitting element. Further, the invention relates to a light emitting element that a spreading electrode is covered by an insulating layer and an intermediate electrode is formed on the spreading electrode.
2. Description of the Related Art
Conventionally, a light emitting element such as a flip-chip type LED is known in which n-side and p-side electrodes are formed on the same side (e.g., JP-A-11-191641, JP-A-2004-153110, JP-A-2004-266296). For example, in JP-A-11-191641, an n-side bump and a-side bump are formed on the n-side electrode and p-side electrode, respectively, and the top surface of the p-side bump is higher than that of the n-side bump. In JP-A-2004-153110 and JP-A-2004-266296, the top surface of the p-side bump is on the same level as that of the n-side bump.
On the other hand, a flip-chip type light emitting element is disclosed which is composed of a p-side spreading electrode, an intermediate electrode on the spreading electrode, a reflection layer on the spreading electrode except a region directly on the intermediate electrode and having a three layer structure of an insulating film, a reflection film and a insulating film, a joining electrode on the insulating film of the reflection layer for feeding current via the intermediate electrode to the spreading electrode (JP-A-2007-300063). Further, JP-A-2001-203386 discloses another light emitting element with plural intermediate electrodes.
However, in JP-A-11-191641, JP-A-2004-153110 and JP-A-2004-266296, where the n-side bump and the p-side bump are of a solder material for bonding the element to a mounting substrate, in case of mounting the light emitting element on the mounting substrate by using the solder material, the light emitting element may be insufficiently parallel to the mounting substrate when the top surface of the p-side bump with a larger area is higher than that of the n-side bump or even when the top surface of the p-side bump is on the same level as that of the n-side bump. In this case, the n-side bump may be unsuccessfully bonded to an electrode pattern on the mounting substrate or voids may be occurred in the n-side bump.
On the other hand, in JP-A-2001-203386, the plural intermediate electrodes may cause difficulty in feeding uniformly current to the entire spreading electrode and thus a decrease in luminous efficiency.